An exposure apparatus, which projects a pattern formed on a mask onto a photosensitive substrate to perform the exposure, is used in the photolithography step as one of the steps of producing microdevices such as semiconductor devices, liquid crystal display devices and the like. The exposure apparatus includes a mask stage for supporting the mask and a substrate stage for supporting the substrate. The pattern of the mask is subjected to the projection exposure onto the substrate via a projection optical system while successively moving the mask stage and the substrate stage. In the microdevice production, it is required to realize a fine and minute pattern to be formed on the substrate in order to achieve a high density of the device. In order to respond to this requirement, it is demanded to realize a higher resolution of the exposure apparatus. A liquid immersion exposure apparatus, in which the exposure process is performed in such a state that the space between the projection optical system and the substrate is filled with a liquid having a refractive index higher than that of the gas, has been contrived as one of means to realize the high resolution, as disclosed in Patent Document 1 as identified below.
PATENT DOCUMENT 1: International Publication No. 99/49504.